On Thu, 14 Nov 2019 at 23:16, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > On Thu, Nov 14, 2019 at 10:33:03PM +0100, Marco Elver wrote: > > On Thu, 14 Nov 2019, Paul E. McKenney wrote: > > > > > On Thu, Nov 14, 2019 at 07:02:53PM +0100, Marco Elver wrote: > > > > This is the patch-series for the Kernel Concurrency Sanitizer (KCSAN). > > > > KCSAN is a sampling watchpoint-based *data race detector*. More details > > > > are included in **Documentation/dev-tools/kcsan.rst**. This patch-series > > > > only enables KCSAN for x86, but we expect adding support for other > > > > architectures is relatively straightforward (we are aware of > > > > experimental ARM64 and POWER support). > > > > > > > > To gather early feedback, we announced KCSAN back in September, and have > > > > integrated the feedback where possible: > > > > http://lkml.kernel.org/r/CANpmjNPJ_bHjfLZCAPV23AXFfiPiyXXqqu72n6TgWzb2Gnu1eA@xxxxxxxxxxxxxx > > > > > > > > The current list of known upstream fixes for data races found by KCSAN > > > > can be found here: > > > > https://github.com/google/ktsan/wiki/KCSAN#upstream-fixes-of-data-races-found-by-kcsan > > > > > > > > We want to point out and acknowledge the work surrounding the LKMM, > > > > including several articles that motivate why data races are dangerous > > > > [1, 2], justifying a data race detector such as KCSAN. > > > > > > > > [1] https://lwn.net/Articles/793253/ > > > > [2] https://lwn.net/Articles/799218/ > > > > > > I queued this and ran a quick rcutorture on it, which completed > > > successfully with quite a few reports. > > > > Great. Many thanks for queuing this in -rcu. And regarding merge window > > you mentioned, we're fine with your assumption to targeting the next > > (v5.6) merge window. > > > > I've just had a look at linux-next to check what a future rebase > > requires: > > > > - There is a change in lib/Kconfig.debug and moving KCSAN to the > > "Generic Kernel Debugging Instruments" section seems appropriate. > > - bitops-instrumented.h was removed and split into 3 files, and needs > > re-inserting the instrumentation into the right places. > > > > Otherwise there are no issues. Let me know what you recommend. > > Sounds good! > > I will be rebasing onto v5.5-rc1 shortly after it comes out. My usual > approach is to fix any conflicts during that rebasing operation. > Does that make sense, or would you prefer to send me a rebased stack at > that point? Either way is fine for me. That's fine with me, thanks! To avoid too much additional churn on your end, I just replied to the bitops patch with a version that will apply with the change to bitops-instrumented infrastructure. Also considering the merge window, we had a discussion and there are some arguments for targeting the v5.5 merge window: - we'd unblock ARM and POWER ports; - we'd unblock people wanting to use the data_race macro; - we'd unblock syzbot just tracking upstream; Unless there are strong reasons to not target v5.5, I leave it to you if you think it's appropriate. Thanks, -- Marco
